Footwear

ABSTRACT

An outsole unit for an item of footwear comprises a base layer of a flexible material having fibres extending from one surface, for example a napped leather such as pigskin suede or a textile material, and one or more lugs of thermoplastic polyurethane (TPU) moulded directly to the fibrous surface so as to form a tread. Multiple lugs may form a regular array separated by grooves, and may be connected solely by the base layer, by a skin of TPU extending across the base layer or by narrow connecting elements of TPU. An upper of an item of footwear may comprise a backing of suede leather with a grid of strips of TPU moulded to its napped surface. An item of footwear may comprise the outsole unit of the invention, the upper of the invention, or both.

The present invention relates to improvements to footwear and components for footwear, and to improved methods for their production. More particularly, but not exclusively, it relates to uppers and outsoles for footwear having improved wear properties and with an improved appearance.

Uppers for footwear may be made from a wide range of materials. Traditional leather uppers are relatively hardwearing and comfortable to wear, and can “breathe”, but require considerable care to keep an attractive appearance. Sueded leather uppers (including true suede and nubuck) are similarly comfortable and “breathable”, but the sueded surface may become shiny where it experiences significant wear. The number of decorative effects that can be achieved with suede or the like is also limited.

There is hence a need for a material from which uppers may be produced that has the advantages of suede or the like, but with fewer of the disadvantages. It would also be beneficial if this material allowed a footwear designer to employ a greater range of decorative effects.

Similarly, while outsoles for footwear have been the focus for much innovation, existing sole units still have shortcomings. For example, injection-moulded polyurethane outsoles are widely used in trainers and other types of footwear. However, these may not be very compliant to a particular wearer's foot shape, usually being monolithic mouldings of a semi-rigid polyurethane composition (softer compositions are too easily damaged on extraction from the mould). Complex structures for outsoles and midsoles have been tried, but these tend to add significantly to the cost of the footwear. Another problem with such outsoles is that they usually have to be mounted to a remainder of the footwear using adhesives. The adhesives currently employed are not very pleasant to use and queries have been raised concerning their environmental soundness.

It is hence an object of the present invention to provide uppers, sole components, footwear, materials from which they may be made and/or methods for their production that obviate the above problems and provide the above advantages.

According to a first aspect of the present invention, there is provided a material adapted to be used in the production of uppers for footwear comprising a first layer of a base material having a plurality of fibrous elements extending from at least a first surface thereof and moulded directly to said first surface an apertured second layer of a composition comprising a thermoplastic polyurethane compound.

Preferably, said base material comprises a leather material having a nap on one surface, such as a suede or nubuck leather.

Said apertured layer may then be moulded to said napped surface.

Said leather material may comprise an artificial or synthetic leather material.

In a first embodiment, the apertured second layer comprises a continuous layer of said composition having a plurality of apertures extending therethrough.

Advantageously, the apertured second layer comprises a plurality of intersecting elongate elements defining apertures therebetween.

Said intersecting elements may be generally linear.

Said intersecting elements may be arranged in a regular array.

The second apertured layer may then form a regular grid.

The apertured layer may comprise occasional unapertured regions.

Preferably, the apertures together comprise at least a third of the apertured layer by area, advantageously at least a half, optionally at least two-thirds.

Preferably, each aperture has a minimum width of less than ten millimetres, advantageously less than five millimetres, optionally less than three millimetres.

In a second embodiment, the apertured second layer is discontinuous, comprising a plurality of unconnected zones of said polyurethane composition.

The base material and the thermoplastic polyurethane composition may be of contrasting colours.

The thermoplastic polyurethane composition may have a Shores hardness of less than 80 C.

According to a second aspect of the present invention, there is provided a method to produce a material to be used in the production of uppers for footwear, comprising the steps of providing a base material having a plurality of fibrous elements extending from at least a first surface thereof and moulding an apertured layer of a composition of a thermoplastic polyurethane compound to said first surface.

Preferably, the method comprises the steps of providing a sheet of sueded leather or other leather material having a napped surface and moulding said apertured layer to said napped surface.

The method may then comprise prior to said moulding step the further step of treating the napped surface to reduce its oil content.

The method preferably comprises the steps of providing a liquid composition curable to form a thermoplastic polyurethane compound, moulding said composition to the base material and curing said composition in contact therewith.

Advantageously, the method comprises the steps of providing mould means adapted to define said apertured layer, introducing said liquid composition into the mould means and so bringing the base material and the mould means together as to contact the base material with the liquid composition.

The method may comprise the step of mixing a plurality of precursor materials to form said liquid composition.

According to a third aspect of the present invention, there is provided an upper for an item of footwear comprising a material as described in the first aspect above.

According to a fourth aspect of the present invention, there is provided an outsole element for an item of footwear comprising a lamina of a flexible material having a plurality of fibrous elements extending from at least a lower, in use, surface thereof and at least one ground contact body comprising a thermoplastic polyurethane composition directly moulded to said lower surface of the lamina.

Advantageously, said lamina comprises a leather material, such as a suede or nubuck leather, having a nap on said lower surface.

Said leather material may comprise an artificial or synthetic leather material.

Alternatively, said lamina comprises a sheet of a woven textile fabric.

Preferably, the outsole element comprises a plurality of said ground contact bodies.

Advantageously, said ground contact bodies are connected, each to the others, by the lamina alone.

Alternatively, said ground contact bodies are connected by linking elements, optionally moulded integrally therewith.

The ground contact bodies may be linked by a skin of said thermoplastic polyurethane composition moulded to the lamina and extending between the bodies.

Preferably, said ground contact bodies comprise a substantially regular array.

A gap between neighbouring ground contact bodies is advantageously substantially narrower than a width of each said body.

Preferably, the lamina extends outwardly of the at least one ground contact body.

It may than comprise a marginal portion adapted to connect the outsole element to a remainder of an item of footwear.

Said marginal portion may be adapted to be sewn to a remainder of the item of footwear.

The thermoplastic polyurethane composition may have a Shores hardness of less than 80 C.

According to a fifth aspect of the present invention, there is provided an method to produce an outsole for an item of footwear comprising the steps of providing a lamina of a flexible material having a plurality of fibrous elements extending from at least a first surface thereof and moulding at least one ground-contact body comprising a thermoplastic polyurethane composition to said first surface.

Preferably, the method comprises the steps of providing a sheet of suede leather or other leather material having a napped surface and moulding said at least one ground contact body to said napped surface.

The method may then comprise prior to said moulding step the further step of treating the napped surface to reduce its oil content.

Alternatively, the method comprises the steps of providing a sheet of woven textile fabric and moulding said at least one ground contact body to one surface thereof.

The method preferably comprises the steps of providing a liquid composition curable to form a thermoplastic polyurethane composition, moulding said composition to the lamina and curing the composition in contact therewith.

Advantageously, the method comprises the steps of providing mould means adapted to define said at least one ground-contact body, introducing said liquid composition into the mould means and so bringing the lamina and the mould means together as to contact the lamina with the liquid composition.

The method may comprise the step of mixing a plurality of precursor materials to form said liquid composition.

According to a sixth aspect of the present invention, there is provided an item of footwear comprising an upper as described in the third aspect above.

According to a seventh aspect of the present invention there is provided an item of footwear comprising an outsole element as described in the fourth aspect above.

According to an eighth aspect of the present invention, there is provided an item of footwear comprising an upper as described in the third aspect above and an outsole element as described in the fourth aspect above.

Preferably, the upper is sewn to the outsole element.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which:

FIG. 1 is an enlarged scrap plan view of a portion of a first material comprising a shoe upper and embodying the present invention;

FIG. 2 is a plan view from below of a first outsole embodying the present invention;

FIG. 3 is a schematic cross-section of the outsole shown in FIG. 2, taken along the line VII-VII;

FIG. 4 is a scrap cross-section of a second outsole embodying the present invention;

FIG. 5 is a scrap cross-section of a third outsole embodying the present invention;

FIG. 6 is a scrap plan view from below of a fourth outsole embodying the present invention; and

FIG. 7 is a side elevation of a training shoe embodying the present invention and comprising the outsole shown in FIG. 2.

Referring now to the Figures, and to FIG. 1 in particular, a small area is shown of a first material 1 from which a shoe upper may be produced. The first material 1 comprises a backing of a conventional sueded leather 2 (here a pigskin suede). A grid of a solid thermoplastic polyurethane composition has been applied directly to a sueded face of the leather 2 by a moulding method described below. In this case, the grid comprises a triangular grid of first strips 3 of the polyurethane (PU) composition, with a plurality of parallel second strips 4 of the PU composition extending across each triangle defined by a trio of first strips 3. The suede leather backing 2 is exposed between the second strips 4. Occasional continuous zones 5 of the PU composition may be included in the grid for decorative effect and/or to provide a location for a logo or trade mark. However, even so, the first material 1 comprises a substantial proportion of uncovered suede leather 2 (here, well over half its area and possibly as much as two thirds thereof).

The first material 1 is thus substantially as breathable as any other suede leather and may be assembled into an upper using the same methods as for conventional suede leather. However, the grid of polyurethane strips 3, 4 mounted to its surface protects it from wear (in this case, each triangle of the grid is roughly a centimetre across, and the second strips 4 are spaced a millimetre or two apart, so the suede 2 is well protected). This allows, for example, suede leathers not of the very top quality to be used for parts of an upper that may be more susceptible to wear (e.g. the toe).

The visual effect of the slightly glossy parallel strips 4 of PU against the matt suede 2 background provides a further design feature usable by a footwear designer, as does the possibility of either sharply-contrasting or subtly-toned colours for the PU 3, 4 and the suede 2.

When the thermoplastic PU is moulded directly to a sueded leather surface or the like it is found that there are no noticeable loss-of-adhesion problems.

The particular PU grid 3, 4 shown in FIG. 1 is just one of many patterns that may be laid down. For example, a hexagonal grid both provides a striking visual effect and protects the suede 2 without covering an excessive proportion thereof.

While the first material 1 illustrated employs a continuous apertured network of PU strips, discontinuous zones of PU may be used instead where strength of the material is not a significant issue.

The moulding process is carried out by providing a horizontally-extending mould matrix for the desired pattern, and filling its concavities with a liquid composition, which is curable to form a thermoplastic polyurethane composition. The suede 2 or other backing material is laid on top of the mould matrix, such that its napped surface contacts an upper surface of the liquid composition and is wetted thereby. The liquid composition is cured, and once the cure is complete and the resultant TPU has cooled, the suede 2 is removed from the mould matrix. The TPU is securely bound to the surface of the suede 2 and releases easily from the mould matrix.

The optimum liquid composition is produced by mixing two liquid TPU precursors, which then begin to react together to form cured TPU. The speed of reaction is selected such that the liquid composition remains fluid and workable for long enough to be introduced into the mould and to wet the suede or the like brought into contact therewith. The heat of the reaction will keep the TPU produced soft and malleable until the cure is complete; the heat then dissipates.

Conventional TPU moulding techniques use pre-cured solid TPU particles which are re-heated until soft, and then injection-moulded to form a required shape. It is probable that the high pressures involved in injection-moulding are necessary to cause such re-heated cured TPU materials to flow satisfactorily into a mould. The materials of the present invention do not require significant pressure to force them into a mould; used at an early stage of the cure, they will flow into a mould relatively easily, and will fill any fine details of the mould matrix, should detailed shapes be required.

Another advantage of the method of the present of the present invention is that softer TPU compositions may be employed than hitherto. The softest TPU compound in general use in the footwear industry has a Shores hardness of 80 C or more; softer TPU compounds are too difficult to de-mould, for example deforming excessively or even tearing as they are removed from a mould. The present method allows TPU compounds with Shores hardnesses in the range of 55 C to 80 C to be used, and no significant de-moulding problems are experienced.

The softer TPU compounds (particularly those in the range of 55 C to 70 C, it is believed) are superior in flex and grip, and also appear to have better anti-abrasion properties than do the harder TPU compounds used hitherto.

As well as pigskin suede, other time suede leathers derived from cow hide or other animal skins may be used. Nubuck leathers are equally useful, as are suede splits. Artificial suedes also work satisfactorily. The common property appears to be a plurality of fibres extending from one surface of the leather or simulated leather, preferably a sufficient density of fibres to form a napped surface.

The technique of directly moulding TPU to a surface of a fibrous substrate is not only of use for materials to make footwear uppers. It is probably of even greater benefit when employed to produce sole components.

FIG. 2 shows a first outsole unit 15 for a training shoe or the like, which comprises a base layer 16 of pigskin suede, to which a plurality of separate blocks or lugs 17 of a solid thermoplastic polyurethane composition have been directly moulded, using a similar process to that described above. As for the materials for the uppers, the TPU lugs 17 are moulded to the sueded face of the pigskin suede 16. Once cured, the TPU composition is similar to those conventionally used for ordinary outsole mouldings, except that it is significantly softer (e.g. Shores hardness 80 C).

In the first outsole unit 15, each lug 17 is generally rectangular and they are separated each from the others by a grid of first grooves 18 extending generally from heel to toe of the outsole unit 15 and second grooves 19 extending generally orthogonally thereto across the outsole unit 15. The exact shape of each lug 17 varies according to its position on the outsole unit; for example, lugs 17A that will be disposed beneath an arch of a wearer's foot, on the “waist” of the sole, are relatively short and narrow, while lugs 17H that will be disposed beneath a wearer's heel are relatively long.

The grooves 18, 19 expose the suede base layer 16, with the result that each TPU lug 17 may move substantially independently of each other lug 17. Thus, when a wearer's weight is placed on the first outsole unit 15, the lugs 17 can move and the base layer 16 flex or stretch to accommodate the wearer's particular foot shape and the distribution of his or her weight across the foot both statically and dynamically. This provides a far more natural feel to a sole comprising the first outsole unit 15 than for a conventional monolithic injection-moulded outsole. The smaller lugs 17A beneath the arch of the foot increase the outsole's flexibility in this area, while the lugs 17H beneath the heel provide support close to that of a conventional shoe heel.

The base layer 16 may alternatively comprise other sueded leathers, such as nubuck, splits and the like (including artificial suede, since breathability is not an issue for an outsole), or a robust woven textile material if preferred. Note: it is known to form conventional monolithic injection-moulded outsoles by injection-moulding heated TPU through a textile fabric from its upper, in use, face. This results in the textile fabric becoming embedded in the TPU moulding, e.g. as a reinforcement. However, it cannot be used on suede or tightly woven fabrics.

Moulding a curable liquid composition directly to a lower, in use, face is simpler, more controllable and easily gives sufficient adhesion, as long as the lower face is substantially oil-free. This also allows the use of softer TPU compositions, since soft TPUs are difficult to remove intact from conventional injection-moulding moulds. TPUs with a Shores hardness of less than 80 C, and even as low as 55 C to 70 C, can be used, which give better sole flexibility and grip than the conventional TPUs with Shores hardness 80 C and above (even before the effect of the sole structure described above is taken into account). The softer TPUs also provide better abrasion resistance.

FIG. 3 shows further advantages of the first outsole unit 15. It is clear from this cross-section that the grooves 19, extending as far as the flexible base layer 16, will allow the lugs 17 substantially independent movement. The base layer 16 comprises a marginal zone 20 which extends outwardly from the outsole unit 15 to all sides (omitted from FIG. 2 for clarity). This marginal zone 20 may be used for mounting the outsole unit 15 to a remainder of a shoe, etc, using conventional stitching techniques, whereas conventional injection-moulded PU soles would almost certainly require adhesives.

Also, an outsole unit 15 may be produced without being restricted to a specific sole profile, because of the flexibility of the base layer 16. This will be described in more detail in respect of FIG. 7 below.

An alternative structure for a second outsole unit 21 is shown in FIG. 4. In this, instead of the grooves 19 extending as far as the base layer 16 so that the lugs 17 are wholly separate, shallower grooves 22 are provided, so that a thin layer or skin 23 of TPU extends across substantially an entire lower surface of the base layer 16. This may be preferred where the base layer 16 is not inherently waterproof, for example, or may be preferred to increase a TPU/base layer contact area for high-performance applications where adhesion is of particular concern. The thin skin 23 does not, however, couple the lugs 17 strongly together, so the second outsole 21 has most of the flexibility, and the ability to conform to a wearer's foot shape and gait, of the first outsole unit 15.

It is also possible, as shown in FIG. 5, to produce a third outsole unit 24 in which a single monolithic TPU outsole 25 is directly moulded to a lower (in use) surface of the base layer 16. While this does not benefit from the very flexible tread surface formed by the lugs 17 of the first and second outsole units 15, 21, it can of course be provided with a conventional tread surface 26, and will still have the benefit of the marginal zone 20 of its base layer 16 for mounting to a remainder of the shoe. It may also comprise a softer TPU composition than is possible with injection-moulding.

Composite outsoles are also envisaged which have a plurality of separate lugs 17 in some regions but monolithic elements 25 in others (e.g. forming a conventional solid heel).

The lugs 17 may, as shown in FIG. 6 in respect of a fourth outsole unit 27, be linked in a different fashion than that shown in FIG. 4. In this case, neighbouring lugs 17 are linked by connecting elements 28, 29 which may extend to the same height as the lugs 17 (elements 29) or be slightly lower (elements 28). The greater the cross-sectional area of each connecting element 28, 29, the more strongly it constrains the respective lugs 17 to move as one. Thus, the lugs 17 may be left to flex freely and independently in some parts of the fourth outsole 27, while they are bound (resiliently) together in others.

FIG. 7 shows a training shoe 30 comprising a first outsole unit 15 mounted to an upper 31. The upper 31 and outsole unit 15 are directly mounted together by stitching through the marginal zone 20 of the outsole unit 15, so no adhesives are required. The upper 31 has been provided with a zone 32 of leather to support the laces 33, and a reinforcement 34 around its toe area to give a structured toecap.

FIG. 7 also shows how the flexible base layer 16 of the outsole unit 15 allows it to adopt a required sole profile. It is currently a common feature of trainer sole design for the outsole to extend significantly up a toe and heel area of the shoe. Here, lugs 17T at a toe end of the outsole unit 15 and lugs 17R at a rear of a heel end thereof may both easily be wrapped around a corresponding portion of the upper 31.

The training shoe 30 produced is thus lightweight, comfortable in wear because of both the breathable upper 31 and the flexible outsole unit 15, and straightforward to produce without the need for adhesives.

Another type of footwear for which outsoles of the type described would be particularly useful is children's shoes. The flexible base layer 16 allows an outsole to stretch gradually as a child's foot grows, where a conventional monolithic outsole might restrict the growing foot.

The natural and synthetic suede leathers and the like, listed above in respect of materials for uppers, can all be used as the flexible base layer 16 of the outsole units 15, 21, 24, 27 described above.

A robust textile fabric may also be used, particularly in situations where a waterproof sole is not required. In this case, the yarns making up the textile will inevitably comprise a large number of free fibre ends which extend away from the yarns themselves (whether the yarns are spun from natural fibres, synthetic fibres or a mixture of each). These “loose ends” appear to be sufficient to ensure good bonding between the textile and the TPU. Penetration of TPU into the textile weave is possible, but is believed to have a secondary effect on the bonding (N.B. many suede leathers and the like have only surface pits adjacent their fibres, which may similarly augment the bonding of the TPU thereto). 

1-28. (canceled)
 29. An outsole element for an item of footwear comprising a lamina of a flexible material having a plurality of fibrous elements extending from a lower, in use, surface thereof and a plurality of ground contact bodies containing a thermoplastics polyurethane composition molded directly to said lower surface of the lamina.
 30. The outsole element according to claim 29, wherein said lamina comprises a leather material having a nap on said lower surface.
 31. The outsole element according to claim 29, wherein said lamina comprises a sheet of a woven textile fabric.
 32. The outsole element according to claim 29, wherein said ground contact bodies are connected, each to the others, by the lamina alone.
 33. The outsole element according to claim 29, wherein said ground contact bodies are connected by linking elements.
 34. The outsole element according to claim 29, wherein the ground contact bodies are linked by a skin of said thermoplastics polyurethane composition molded to the lamina and extending between the bodies.
 35. The outsole element according to claim 29, wherein said ground contact bodies comprise a substantially regular array.
 36. The outsole element according to claim 29, wherein the lamina comprises a marginal portion adapted to be sewn to a remainder of the item of footwear.
 37. The outsole element according to claim 29, incorporated into an item of footwear.
 38. A method of producing an outsole for an item of footwear, comprising the steps of providing a lamina of a flexible material having a plurality of fibrous elements extending from a first surface thereof and molding a plurality of ground-contact bodies comprising a thermoplastic polyurethane composition to said first surface.
 39. A method of producing an insole according to claim 38, comprising the steps of providing a sheet of leather material having a napped surface and molding said ground contact bodies to said napped surface.
 40. The method according to claim 38, comprising the further step of treating the napped surface prior to said molding step to reduce an oil content of the napped surface.
 41. The method according to claim 38, comprising the steps of providing a sheet of woven textile fabric and molding said plurality of ground contact bodies to one surface of said sheet of woven textile fabric.
 42. The method according to claim 38, comprising the steps of providing a liquid composition curable to form a thermoplastic polyurethane composition, molding said composition to the lamina and curing the composition in contact therewith.
 43. A material adapted to be used in the production of uppers for footwear comprising a first layer of a base material having a plurality of fibrous elements extending from a first surface thereof and molded directly to said first surface an apertured second layer of a composition comprising a thermoplastic polyurethane compound.
 44. A material according to claim 43, wherein said base material comprises a leather material having a nap on one surface and said apertured layer is molded to said napped surface.
 45. A material according to claim 43, wherein the apertured second layer comprises a continuous layer of said composition having a plurality of apertures extending therethrough.
 46. A material according to claims 43, wherein the apertured second layer comprises a plurality of intersecting elongate elements defining apertures therebetween.
 47. A material according to claim 43, wherein the apertured second layer is discontinuous, said second layer comprising a plurality of unconnected zones of said polyurethane composition.
 48. A material according to claim 43, incorporated into an upper for an item of footwear.
 49. A method of producing a material to be used in the production of uppers for footwear comprising the steps of providing a base material having a plurality of fibrous elements extending from a first surface thereof and molding an apertured layer of a composition of a thermoplastic polyurethane compound to said first surface.
 50. The method according to claim 49, comprising the steps of providing a sheet of leather material having a napped surface and molding said apertured layer to said napped surface.
 51. The method according to claim 50, comprising the further step of treating the napped surface prior to said molding step to reduce its oil content. 